1. Field of the Invention
This invention relates to novel methods for making a carpet having a secondary backing which is substantially impervious to liquids. The methods involve applying a repellent finish onto the secondary backing material. The invention also encompasses carpets made from such methods.
2. Description of Related Art
The majority of residential and commercial carpets are constructed in the following general manner. Carpet pile yarn is first inserted through a primary backing fabric to form tufts of yarn projecting from the surface of the fabric. The carpet is then dyed. The primary backing is then coated with a polymeric latex to lock the yarn tufts in place and to provide an adhesive for a secondary backing fabric. The latex-coated primary backing is then bonded to the secondary backing to form a laminated backing structure.
However, one problem with the above-described carpets is their susceptibility to penetration by liquids. For instance, if water, a water-based liquid (soda pop, coffee, urine, etc.), or another type of liquid (e.g., oil-based) is spilled onto the carpet face, it may permeate through the primary and secondary backings and onto the underlying material (carpet underpad, hardwood floors, etc.). The underlying material may become stained and deteriorate over a period of time. Mildew may also grow on the backing and underlying material.
Those skilled in the trade have considered different ways for manufacturing latex-backed carpets in order to reduce the permeability of liquids through the primary backing material.
One method involves applying a fluorochemical or other water-repellent agent onto the face fiber of the carpet during the fiber-forming or carpet-manufacturing process. In such instances, the fluorochemicals serve to reduce the wettability of the fibers in the finished carpet such that a spilled liquid will initially "bead" on the surface of the fiber. However, if the beaded liquid is not promptly removed, it will eventually be absorbed by the fibers and may penetrate through the primary backing.
Another method for making the primary backing impervious to liquids involves mixing fluorochemicals into the latex composition and then coating the primary carpet backing with the fluorochemical-containing latex.
For instance, Ucci, U.S. Pat. No. 4,643,930, discloses a carpet structure having a primary backing tufted with nylon yarns. The yarns are coated with a fluorochemical to improve the soil resistance of the carpet. The underside of the primary backing is coated with a latex containing fluorochemicals mixed therein such that the primary backing is made substantially impervious to water.
Blyth et al., U.S. Pat. No. 4,619,853 also discloses nylon carpets having a primary backing coated with a latex containing fluorochemicals mixed therein. In addition, the nylon yarns are coated with sulfonated phenol or naphthol-formaldehyde condensate to improve the stain resistance of the carpet's surface.
Ucci, U.S. Pat. No. 4,579,762 also discloses nylon carpets having a primary backing which is coated with a fluorochemical-containing latex. In this instance, the nylon yarns are made from a modified nylon polymer containing aromatic sulfonate units to improve the stain-resistance of the carpet's surface.
Although the foregoing methods may be somewhat effective for providing the primary backing with water impermeability properties, such methods may restrict the flexibility of the carpet manufacturing operation. For example, it may not be possible to continuously convert a commercial production unit in order that batches of fluorochemical-containing latex are applied to some primary backings, while batches of standard, non-fluorochemical-containing latex are applied to other primary backings. Additionally, in some instances, stainings on carpets having impervious primary backings may be more visible since the stain will not penetrate into the primary backing but may spread across the face of the carpet. In addition, if such carpets also have a secondary backing, the latex containing the mixed fluorochemicals may reduce the adhesion between the primary and secondary backings, thus reducing the delamination strength and tuft bind of the carpet.
In view of the above disadvantages, it would be desirable to have a method for making the secondary backing of a carpet substantially impervious to liquids, and such a method should also be commercially flexible for manufacturing the carpets. The present invention provides such methods as well as the resultant carpets having a secondary backing substantially impervious to liquids.